I suggest you take it to social media. I think you should complain on Twitter and Royal's Facebook page. If it was a computer glitch than you are not the only one it affected. If you can find others and you all complain on social media you may get them to honor it. It worked for the Deluxe Drink package glitch in July. People bought the drink package for $18 knowing it was a mistake and when Royal said they would have to cancel it and rebook people took to social media and complained. Royal caved and now people have the deal of a life time.
BTW, according to the clause you quoted Royal was supposed to cancel your booking. If they won't honor the original price then you should at the very least get your entire deposit back without penalty based on the clause they are using to change the price because you didn't approve the booking. Good luck.